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Re: DTD Notation raises a question

Ya know, there always seems to be a counterexample to the statement "the 
different productions A and B are semantically equivalent".

In Linguistics, it is well known that true synonomy does not exist.  Given 
two putative semantic synonyms (like "medial" and "middle") -- one can always 
find a discourse pragmatic usage of one where the other would not be allowed 
("I am the middle child", *"I am the medial child.").

Since our production rules for XML define a limited form of a language, 
perhaps it would useful to keep in mind that, like in languages, different 
forms cannot be universally (i.e. in all contexts) synonymous.  This may seem 
like a rather whoo-whoo kind of statement but I guess it is motivated by the 
thought that I have only seem determinism discussed in  the context of 
parsing, not in terms of generation.   

The example provided by Deborah Aleyne Lapeyre below raises this question in 
a very specific and easily resolvable setting.  Specifically, two content 
models which are initially seen as equivalent (applying the generalization 
that extraneous parentheses do not change the model),  but yet produce 
different sets of "sentences".  I

Anyone one done any work in this area or have any references?  It is 
something I am unfamiliar with and I'd love to read up on it.


On Wednesday 11 July 2001 03:45 pm, Deborah Aleyne Lapeyre wrote:
> >What's the difference between "ItemC*" and "(ItemC)*"?
> None, as everybody already said.
> Parens ALMOST never matter.
> That said, there is one warning.  Since #PCDATA must
> be first in any grouping, there is a big difference
> between:
> (#PCDATA | itemC)*   (valid)
> and the invalid
> ((#PCDATA | itemC))*
> --Debbie

Rod Davison @ Critical Knowledge Systems Inc
"Historically speaking, the presence of wheels in Unix has never precluded 
their reinvention." - Larry Wall